Do you know why uptime -s increasing in Azure platform?
hostname@ubuntu:~$ date
Thu Jan 4 15:00:04 CET 2018
hostname@ubuntu:~$ uptime -s
2018-01-01 00:52:15
After 10 minutes:
hostname@ubuntu:~$ date
Thu Jan 4 15:10:18 CET 2018
hostname@ubuntu:~$ uptime -s
2018-01-01 00:52:24
hostname@ubuntu:~$ ps -Afl F S UID PID PPID C PRI NI ADDR SZ WCHAN STIME TTY TIME CMD 4 S root 1 0 0 80 0 - 30225 - Jan01 ? 00:00:49 /sbin/init
This host works stable
The apparent time that your system was booted, as shown by uptime -s, changed because the system clock changed.
Let us look at the source code for uptime, to see how it works.
/* Get the current time and convert it to a double */
gettimeofday(&tim, NULL);
now = tim.tv_sec + (tim.tv_usec / 1000000.0);
We see here that it first gets the current time of day.
/* Get the uptime and calculate when that was */
uptime(&uptime_secs, &idle_secs);
up_since_secs = (time_t) ((now - uptime_secs) + 0.5);
Next, it gets the actual uptime in seconds as reported by the kernel, and which would otherwise have been reported if you hadn't used -s. It then subtracts that number of seconds from the current time, rounding to the nearest second.
Thus, if the system clock is adjusted, the output of -s will have a corresponding change.
